The present invention relates to fluid-operated tools, such as for example hydraulic wrenches and the like.
Fluid-operated tools of this type are known in the art. In a known fluid-operated tool an engaging means engage a threaded connector to be tightened or loosened and turn the threaded connector correspondingly, while a driving means is connected with the engaging means so as to apply the driving force and to turn the engaging means correspondingly. In the known fluid-operated means, the driving means usually include a fluid-operated cylinder-piston unit. It is well known that during tightening of a threaded connector it is first of all necessary to turn the threaded connector or to run it down into an object over a long stroke, and then at a final stage to apply a greater torque over a short stroke to provide the tightening itself. During loosening of the threaded connector the situation is reversed, in particular it is first necessary to apply a substantial torque to loosen a threaded connector and then to run the threaded connector off the object over a long stroke. In the known fluid-operated tool the tightening and loosening of the threaded connector performed with the same fluid-operated driving means is carried out with the same speed through both stages of the process. However, as explained hereinabove, the first stage of the tightening does not require a great torque but instead requires a longer run connected with a longer time, while the further stage of the tightening requires a greater torque and a shorter run. Usually, the tools are designed so as to provide the slow and high-torque tightening, and therefore the stages of running-down and running-off are very slow and take a long time.